Alien spacecraft problem

Question

HI. I'm having trouble with a game I'm trying to make, when I try to reference the bullets it fires it keeps coming up with Error #1010: A term is undefined and has no properties. It's doing this when I try to reference a alien spacecraft bullet in the "update" function. I've marked what line the error occurs on. And the bullets don't move. If anyone can help please do. Here's the code: Again, I get the error in the update function.
package enemyObjects
// Import necessary classes from the flash libraries
import flash.display.Sprite
import flash.geom.Point;
import flash.events.MouseEvent;
import flash.ui.Mouse;
import flash.utils.Timer;
import flash.events.TimerEvent;
import tileSheetStuff.*;
import gameElements.effects.*;
import gameMVC.*;
* @author Steve Fulton
public class AlienShot extends Sprite
private var startLocation:Point;
private var endLocation:Point;
private var xunits:Number;
private var yunits:Number;
private var nextLocation:Point;
private var leftNextLocation:Point;
private var moves:int = 0;
public var finished:Boolean;
private var notHit:Boolean = true;
public var bulletDir:int = 1;
public var enemyShot:BlitSprite;
public var enemyShotLeft:BlitSprite;
private var _bulletSpeed:Number = 23;
private var _tileWidth:int = 112;
private var _tileHeight:int = 112;
private var _spriteGridClass:SpriteGridClass = new SpriteGridClass();
private var _tileSheet:TileSheet = new TileSheet(new SpriteGrid(0,0), _tileWidth, _tileHeight);
private var _gameModel:GameModel;
public function AlienShot (startX:Number, startY:Number, _gameModel:GameModel,bullDir:int) {
this._gameModel = _gameModel;
startLocation = new Point(startX,startY);
this.bulletDir = bullDir;
nextLocation = new Point(0,0);
leftNextLocation = new Point(0,0);
_spriteGridClass.initTileSheetData();
_bulletSpeed = 23;
init();
public function init():void {
var enemyShot:BlitSprite = new BlitSprite(_tileSheet, _spriteGridClass.enemyBulletFrame, 0);
this.enemyShot = enemyShot;
enemyShot.x = startLocation.x;
enemyShot.y = startLocation.y;
var enemyShotLeft:BlitSprite = new BlitSprite(_tileSheet, _spriteGridClass.enemyBulletFrame, 0);
this.enemyShotLeft = enemyShotLeft;
enemyShotLeft.x = startLocation.x;
enemyShotLeft.y = startLocation.y;
//***** Flash *****
enemyShot.currentTile =  0;
enemyShot.scaleX= 1;
enemyShot.scaleY= 1;
if(bulletDir == -1){
_gameModel.alienBulletModels.push(enemyShot);
_gameModel.enemyShot = enemyShot;
_gameModel.screen.addChild(enemyShot);
}else if(bulletDir == 1){
_gameModel.alienBulletModelsLeft.push(enemyShotLeft);
_gameModel.playerShotLeft = enemyShotLeft;
_gameModel.screen.addChild(enemyShotLeft);
finished = false;
public function update():void {
for(var i:int = _gameModel.alienBulletModels.length; i > 0; i--)
if (notHit = true) {
nextLocation.x = _gameModel.alienBulletModels[i].x + _bulletSpeed;------------>ERROR OCCURS HERE BECAUSE OF THE ALIENBULLETMODELS
nextLocation.y = _gameModel.alienBulletModels[i].y;
} else {
finished = true;
_gameModel.alienBulletModels[i].x = nextLocation.x;
_gameModel.alienBulletModels[i].y = nextLocation.y;
for(var j:int = _gameModel.alienBulletModelsLeft.length; j > 0; j--)
if (notHit = true) {
leftNextLocation.x = _gameModel.alienBulletModelsLeft[j].x -_bulletSpeed;
leftNextLocation.y = _gameModel.alienBulletModelsLeft[j].y;
} else {
finished = true;
_gameModel.alienBulletModelsLeft[j].x = leftNextLocation.x;
_gameModel.alienBulletModelsLeft[j].y = leftNextLocation.y;
if((_gameModel.alienBulletModels[i].x < 0)||(_gameModel.alienBulletModels[i].x >550)){
dispose(_gameModel.alienBulletModels[i],i);
if((_gameModel.alienBulletModels[i].y < 0)||(_gameModel.alienBulletModels[i].y >400)){
dispose(_gameModel.alienBulletModels[i],i);
if((_gameModel.alienBulletModelsLeft[j].x < 0)||(_gameModel.alienBulletModelsLeft[j].x >550)){
disposeLeft(_gameModel.alienBulletModelsLeft[i],i);
if((_gameModel.alienBulletModelsLeft[j].y < 0)||(_gameModel.alienBulletModelsLeft[j].y >400)){
disposeLeft(_gameModel.alienBulletModelsLeft[i],i);
//Dispose is needed to get rid oo unwanted objects and get them ready for garbage collection
public function dispose(object:BlitSprite,i):void {
_gameModel.screen.removeChild(object);
_gameModel.alienBulletModels.splice(i,1)
_gameModel.alienBulletModels[i] = null;
public function disposeLeft(object:BlitSprite,j):void {
_gameModel.screen.removeChild(object);
_gameModel.alienBulletModelsLeft.splice(j,1)
_gameModel.alienBulletModelsLeft[j] = null;

Answer 1

You may need to convert your bullet image to a movieclip if you haven't and give it a instance name.
also define it.
For example:
private var bullet_mc:MovieClip;
Also an instance name for that specific movieclip:  e.g: "bullet"
Hope that helps.